Granular smokeless powder with peroxide coating



3,1 17,643 Patented Jan. 7, 1964 of Delaware No Drawing. Filed Sept. 20, 1965, Ser. No. 57,159 12 Claims. (Cl. 149-116)) This invention relates to a powder suitable for use as a propellant for small arms ammunition and for use as an igniting charge in heavy ordnance.

For many years black powder was the only propellent powder known but it has been for most purposes replaced by smokeless powder composed principally of nitrocellu lose, in some instances with the addition of nitroglycerine to make a double base powder and nitroguanidine to make a triple base powder. Only in the field of igniting charges for heavy ordnance has black powder continued in substantial use and there principally because of its susceptibility to ignition by flame.

Among the benefits to be gained by the substitution of smokeless powder for black powder for all purposes are the following:

(1) Less hygroscopic (2) Less residue in the barrel, and fewer residue products which would lead to rusting in the bore (3) Greater density (4) Higher spontaneous explosion temperature (5) More reproducible sources of supply With respect to the first and second points, the moisture absorption characteristics of the ingredients of which black powder is a mixture are well known, and it is also well known that the products of combination are also hygroscopic and highly cororsive. It is known that only very small percentages of potassium and sulfur compounds will cause severe corrosion and the trouble will not be eliminated by using small percentages of black powder in admixture with or adhesively secured to smokeless powder, as disclosed in US. Patent No. 1,354,640.

The volume of smokeless powder is approximately 64% of that of black powder, in order to produce the same energy level, which opens the possibilty of decreasing the dimensions of cartridge cases and igniter containers.

Black powder explodes when heated for about 5 seconds to about 190 C., while smokeless powder will withstand, without explosion, temperatures Of about 315 for almost 5 seconds.

In the use of single, double or triple base smokeless powders in ammunition loading, there are some situations where the ability of the primer to ignite the charge is borderline, and attempts have been made to alleviate this problem by the use of hotter primers and in some instances by the use of igniting charges of black powder. Examples of this are found in the loading of shotshells with magnum charges, in the loading of certain centerfire cartridges such as .30-06- Springfield and .270 Win. with ball type propellent powder and in smokeless powder loading of some of the old large capacity black powder cartridges, such as .38/ 40, .44/40 and others, where the case is only partly filled with smokeless powder.

The object of my invention is to produce a smokeless powder which more nearly approaches the sensitivity to ignition by flame of black powder for use either in conventional ammunition as a propellant or in heavy ordnance as an igniting charge.

I contemplate that the best method of improving the ignition sensitivity of smokeles powder is to coat the surface of the powder grains with a material which makes the surface more flame sensitive and yet does not alter the linear burning rate of the powder grain beneath the surface which characterizes smokeless powder compositions. Obviously the ignition promoting coating must be one which is itself non-corrosive and non-hygroscopic and one which does not produce hygroscopic or corrosive products of combustion.

I have found that I can coat the surface of smokeless powder grains with certain oxidizing agents which meet the criteria above with respect to corrosiveness and hygroscopicity. Certain metallic peroxides have been found to be particularly suitable for this application. When tested for ignition susceptibility, it can be shown that an improvement has been effected by about a factor of three and yet ballistic performance in conventional ammunition has not been substantially affected.

The peroxides of lead, barium and strontium, are all non-hygroscopic and non-corrosive and when they react with smokeless powder during the burning thereof produce neither hygroscopic or corrosive products. When any of these peroxides have been coated on the surface of smokeless powder grains they greatly improve the susceptibility of the powder to ignition by flame. Particularly with smokeless powder which has not been glazed with graphite, the coating may be applied simply by tumbling the smokeless powder grains in the presence of the peroxide. With lead or strontium peroxides, useful results are obtained by tumbling even graphite glazed powder with the peroxide.

To evaluate ignition susceptibility, I have laid powder trains by filling a groove milled in a block of steel, igniting one of the powder train and measuring the time to propagate the flame along the 10" length of the powder train. Ballistic effects have been evaluated by loading identical charge weights in standard ammunition and recording pressure and bullet velocity.

For example, a sample of double base powder Du Pont #6399 was surface coated by tumbling 200 grams of powder with 5 grams of lead peroxide for 30 minutes in a ball mill. Comparative tests of flame propagation along the powder train described above show an improvement by a factor of three, as compared to the uncoated #6399 powder. When such powders were loaded into 22 caliber long rifle high speed ammunition, however, the coated powder actually showed a modest but perhaps not statistically significant decrease in pressure level and velocity, rather than the increase which might have been expected from the increased burning rate. Specifically one series of tests showed for the coated powder a velocity of 1267 feet/second and pressure of 20,690 p.s.i., while the uncoated powder showed a velocity of 1318 feet/ second and pressure of 22,450 p.s.i.

Du Pont No. 6399 is a pressed and cut, double base, porous propellant in the form of small discs consisting of about parts nitrocellulose, 15 parts nitroglycerin, and a small amount, up to about 10 parts, of a stabilizing agent such as diphenylamine, and a moderant such as dinitrotoluene.

Similar tests with Du Pont #7655 a glazed single base powder coated in about the same proportions as shown above when compared with unmodified #7655 powder as a control and with #7655 powder which has been tumbled in a ball mill without any additive are as follows:

Burning rate per 10 inches Black powder of FFFG Super Fine granulation, sold by Du Pont for small rifle and shotshell use, shows under the same conditions a burning rate per inches of approximately 1 second.

Du Pont No. 7655 is a pressed and cut, single base, porous powder in the form of small discs consisting of 92% nitrocellulose, 4-5 of a moderant such as dinitrotoluene, and the remainder a stabilizing agent such as diphenylamine and residual moisture.

Although I prefer to avoid the use of any adhesive substance or solvent for smokeless powder as a means of promoting adhesion of the metallic peroxide, I consider that any means of effecting a surface coating of the smokeless powder grains with such a peroxide comes Within the scope of my invention. Where smokeless powder is referred to in the claims, I wish it to be understood to include single, double or triple base powders.

Accordingly, I wish it to be understood that I consider the scope of my invention to be limited only by the following claims.

I claim:

1. A propellent powder consisting essentially of smokeless powder grains having an adherent coating of a metallic peroxide selected from the group consisting of the peroxides of barium, strontium and lead.

2. A propellent powder consisting essentially of smokeless powder grains having an adherent coating of barium peroxide.

3. A propellent powder consisting essentially of smokeless powder grains having an adherent coating of strontium peroxide.

4. A propellent powder consisting essentially of smokeless powder grains having an adherent coating of lead peroxide.

5. A process of improving the ignition susceptibility of smokeless powder, which comprises applying to the surface of grains of said powder an adherent coating of a metallic peroxide selected from the group consisting of the peroxides of barium, strontium and lead.

6. A process of improving the ignition susceptibility of smokeless powder, which comprises applying to the surface of grains of said powder an adherent coating of barium peroxide.

7. A process of improving the ignition susceptibility of smokeless powder, which comprises applying to the surface of grains of said powder an adherent coating of strontium peroxide.

8. A process of improving the ignition susceptibility of smokeless powder, which comprises applying to the surface of grains of said powder an adherent coating of lead peroxide.

9. A process of improving the ignition susceptibility of smokeless powder, which comprises tumbling grains of said powder with an adherent form of a metallic peroxide selected from the group consisting of the peroxides of barium, strontium and lead.

10. A process of improving the ignition susceptibility of smokeless powder, which comprises tumbling grains of said powder with an adherent powdered form of barium peroxide.

11. A process of improving the ignition susceptibility of smokeless powder, which comprises tumbling grains of said powder with an adherent powdered form of strontium peroxide.

12. A process of improving the ignition susceptibility of smokeless powder, which comprises tumbling grains of said powder with an adherent powdered form of lead peroxide.

References Qited in the file of this patent UNITED STATES PATENTS 2,865,729 Foster et al Dec. 23, 1958 FOREIGN PATENTS 575,860 Great Britain 149/10 OTHER REFERENCES Bebie: Manual of Military Pyrotechnics and Chemical Warfare Agents, 1943, pp. 31, 92, 141. 

1. A PROPELLENT POWDER CONSISTING ESSENTIALLY OF SMOKELESS POWDER GRAINS HAVING AN ADHERENT COATING OF A METALLIC PEROXIDE SELECTED FROM THE GROUP CONSISTING OF THE PEROXIDES OF BARIUM, STRONTIUM AND LEAD. 